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Answers
Answer:
Three Marks Questions.
1.The strength of gravity depends on the masses of each object and also distance between them. All objects experience an attraction toward all other objects. But earth's mass is so large it makes gravitational pull of all other objects on Earth unnoticeable.
2.Acceleration due to gravity is independent of mass. These two quantities are independent of each other. Light objects accelerate more slowly than heavy objects when force other then gravity are also at work. In this case the object is fallling but it is not considered as a free fall.
Five Marks Questions.
3.Archimedes, the Ancient Greek scientist first stated the principle of floatation. According to him, all the objects placed in a liquid experience an upward force which allows the body to float if it displaces water with the weight equal to the weight of the body. This upward force is known as buoyant force and the law is known as the law of buoyancy. Mainly, floatation depends upon the density. If an object has a density less than the density of water, it floats. Like, leaf of a plant floats on the water because the density of leaf is less than the density of water. A stone thrown in water sinks because the density of stone is more than the density of water.
Principle of Archimedes :
When a body is immersed partly or wholly in a liquid, there is an apparent loss in the weight of the body which is equal to the weight of liquid displaced by the body.
Laws of Flotation :
A body floats in a liquid if :
1. Density of the material of the body is less than or equal to the density of the liquid.
2. If density of material of body is equal to density of liquid, the body floats fully submerged in liquid in neutral equilibrium.
3. When body floats in neutral equilibrium, the weight of the body is equal to the weight of displaced liquid.
Explanation: